The goals of this research are: 1) better understand the mechanisms by which cells, especially blood cells, differentiate from an immature to a functioning state, 2) to determine the levels of control of differentiation which are altered in poorly differentiated leukemic or other neoplastic cells. Present studies involve characterizing changes in the protein gene products of HL-60 cells when stimulated to differentiate by chemical inducers, and also characterizing mRNA produced during that process.